Conventionally, a semiconductor device that includes a reverse conducting (RC)—IGBT structure in which IGBT and FWD together are provided to a single chip has been proposed (for example, see a patent literature 1). In the RC-IGBT structure, IGBT is configured from a trench gate structure, and FWD is positioned between the trench gates. A width of the narrowest part between the trench gates in IGBT (hereinafter referred to as a mesa width) is set to be equal to a mesa width in FWD.
However, by a recent miniaturization and an introduction of the RC-IGBT structure with a narrowed mesa width IGBT in which the mesa width is reduced, when the mesa width of FWD is reduced to match to the mesa width of IGBT, it is observed that a diode characteristic of FWD changes sharply. In other words, it is observed that, in a case that the diode is configured between the trench gates, when the mesa width is too reduced, it may be difficult to perform a characteristic control and a variation suppression.